Methods and Apparatuses For Enhanced In Situ Hydrocarbon Production

Abstract

A process for recovering hydrocarbons from an in situ formation. The process includes the steps of injecting solvent though an injection well into an underground extraction chamber having a hydrocarbon extraction interface, warming the hydrocarbons at the extraction interface to cause the hydrocarbons to flow downwardly by gravity drainage. Barrier gases naturally emerge in the chamber as a result of the extraction process and are removed from the extraction interface to improve heat transfer from said solvent to said interface. The last step is to recover liquids such as hydrocarbons and water through a production well. The invention provides a separate flow path to remove hydrocarbon gases from the chamber at a preferred location. The preferred location is near the top of the chamber where the accumulated barrier gases help to limit the heat loss and can also provide a barrier to help maintain chamber integrity and confinement.

Description

FIELD OF THE INVENTION[0001]This invention relates generally to the recovery of hydrocarbons such as heavy oil or bitumen from underground hydrocarbon bearing formations. In particular, this invention relates to the in situ recovery of such hydrocarbons through the use of gravity drainage techniques.BACKGROUND OF THE INVENTION[0002]Gravity drainage is a known technique for the in situ extraction of hydrocarbons. At present it is mainly performed by the injection of steam into the hydrocarbon bearing formation. However, it may also be performed by the injection of a solvent. Essentially, in a gravity drainage extraction process, the steam or solvent vapour is injected into a formation from a generally horizontal injection well and recovered from a lower parallel-running generally horizontal production well. An extraction chamber gradually develops in the formation as the oil or bitumen is removed from the reservoir above and between the wells. As the vapour flows towards the perimete...

AI Technical Summary

Benefits of technology

[0007]The present invention is directed to improved methods and apparatuses to remove less condensable barrier gases from the gravity drainage extraction chamber. The removal of such gases is desirable to permit a condensing solvent process to deliver heat (heat transfer) to the hydrocarbon extraction interface and to deliver high solvent concentrations to the extraction interface to improve the dilution effect (mass transfer) of the solvent on the hydrocarbons being extracted. Improved methods and apparatuses are desired to allow a solvent extraction process to be effective at chamber extraction conditions in which the amount of such gases present in the chamber is higher than can be reliably removed by the draining liquids alone.

[0008]The present invention is further directed to methods and apparatuses for a solvent extraction process that can remove less condensable gases from deeper reservoirs where the amount of naturally occurring dissolved gas within the hydrocarbons in place is typically higher than in shallower reservoirs. Where conditions permit, it is an aspect of this invention to operate in deeper reservoirs at pressures less than the original in situ pressure, which can permit condensing solvent conditions to be established in the deeper reservoir, but which will create a larger off gas or barrier gas problem. The methods and apparatuses of the present invention can be used in such reduced pressure extraction conditions to manage and remove the more prevalent non-condensable barrier gases.

[0009]The present invention is further directed to methods and apparatuses for a solvent extraction process that can remove less condensable gases from extraction chambers which are being operated at solvent to oil ratios (SOR) which are too low to remove, as liquids, enough of the barrier gases. At lower solvent to oil ratios the ability of the solvent to carry off the non-condensable gases as liquids is also reduced and the methods and apparatuses of the present invention can be used to manage and remove the excess barrier gases which are present within the chamber as a result of the extraction process. Lower SOR can be desirable for example by being able to decrease the extraction costs, by lowering the amount of solvent used and processing required.

Problems solved by technology

These temperatures result in a condensation of the vapour and the transfer of heat to the sand and bitumen, causing the bitumen to warm up.

Such gases tend to be left behind in the extraction chamber as the solvent condenses and thus tend to accumulate in the chamber.

However, solvent extraction processes have not yet been proven in the field.

Further, as the solvent extraction process is applied to deeper and more gassy hydrocarbon reservoirs, it becomes increasingly difficult to avoid the accumulation of non-condensable gas in the chamber and the consequent loss in extraction rate.

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